ACCEL interviews and topical summaries of cardiology’s most interesting research areas. RESET-HCM: Exercise Regimens in Patients with Hypertrophic Cardiomyopathy In this ACCEL interview, Peter C. Block, MD, FACC, is joined by Sara Saberi, MD, to talk about the results of RESET-HCM, a randomized exploratory study of exercise training in hypertrophic cardiomyopathy. Dr. Block: Dr. Saberi, please tell us about the RESET-HCM study. Dr. Saberi: We randomized patients with hypertrophic cardiomyopathy to one of two exercise regimens: usual activity or moderate intensity exercise prescribed for a 16-week period that was individualized for each patient based on their heart rate reserve. The primary outcome was change in peak VO2. Traditionally patients with hypertrophic cardiomyopathy have been told not to exercise. Why did you do this study and is it safe? That’s exactly why we did this. In clinic appointment after clinic appointment, patients would tell us how much they were affected by the fact that they couldn’t exercise or were told not to exercise. And more than anything the fear that drives into their hearts that something bad could happen to them if they’re running or walking or even climbing the stairs at home. That’s why we pursued doing this study – to try to answer the question of whether light-to-moderate-intensity exercise could potentially have some benefits for these patients. Emphasis here on light to moderate? More like moderate. The exercise intensity targeted moderate intensity exercise. How much did they work? In the first week on protocol, they did three sessions of exercise, at least 20 minutes, targeting a heart rate reserve of 60 percent, with a Borg Rating of Perceived Exertion of 11 to 14. So, really in the moderate range. In weeks two to four, they had four to seven sessions a week. The exercise duration was increased by five to 10 minutes each week, up to 60 minutes, and the intensity was at 70 percent of the heart rate reserve. For the rest of the trial, from weeks five through 16, they were charged with maintaining their exercise regimen. What did they do? Elliptical work? The majority of patients had a walking regimen. They just needed a pair of shoes to walk around the block. Some patients did some jogging, light running, elliptical, cycling and stair climbing. Several patients also did swimming and rowing. You compared those who did not exercise with those who exercised. What was the difference between the two groups? The difference was a statistically significant improvement in peak VO2. The exercise group had a 1.27 mL/kg/min improvement in peak VO2 over the usual activity group. This corresponds to about a 6 percent increase in oxygen consumption. We also found they had improved quality of life by one measure of the Short Form (SF)-36 scale. So this comes down to if you exercise, you feel better? You do feel better. I think that’s been proven in all kinds of other patient populations and in the general population as well. What does this mean for the patient with hypertrophic cardiomyopathy? The focus in the management of hypertrophic cardiomyopathy for decades has been ventricular arrhythmias and sudden cardiac death. In RESET-HCM, there was absolutely no major adverse events. There was no occurrence of death, sudden cardiac death, aborted sudden cardiac death and appropriate ICD therapies. Additionally, there were no difference between the groups for minor adverse events, including nonsustained ventricular tachycardia, atrial fibrillation, supraventricular tachycardia and musculoskeletal injuries. I think what this means for patients with hypertrophic cardiomyopathy and their providers is that we can all feel more comfortable encouraging patients with hypertrophic cardiomyopathy to exercise. Let’s drill down a little bit because something must’ve been a little bit different. Did the number of premature ventricular contractions (PVCs) go up, for example? No. The PVC burden was reduced. We did a 24-hour Holter monitor on the initial testing day and at follow-up. All patients wore a 30-day arrhythmia detection monitor continuously – a 24/7 kind of monitor for 30 days. We found the PVC burden was reduced in the exercise group over the usual activity group. We don’t know what that means exactly, but it’s encouraging that at least we’re not incurring more arrhythmias and more electrical instability. As a clinician looking back at these data, what do you say to the folks taking care of hypertrophic disease? How bad does the disease have to be before worrying about exercise? And how good is exercise for patients with severe disease? Our study population would not be considered low risk. About a third of patients reported NYHA Class II or III symptoms. Sixteen percent had resting obstruction. Another 26 percent already had a septal reduction procedure, so their resting obstruction had been dealt with already. And 16 percent had a history of atrial fibrillation and 4 percent had a history of ventricular tachycardia, ventricular fibrillation or aborted sudden cardiac death. These numbers were very representative of our general institution’s patient population in terms of hypertrophic cardiomyopathy based on characteristics and were similar with those of published series. In a kind of average and representative hypertrophic cardiomyopathy population, we found that exercise had beneficial effects in terms of functional capacity. Lower peak VO2 has been associated with increased mortality and adverse outcomes in hypertrophic cardiomyopathy. So, to find something as simple as an easy walking program that could improve peak VO2 is a game-changer in this field. If I had a patient with hypertrophic disease, what am I going to tell them? I would encourage you to learn more about the baseline functional capacity of your patient. Maybe start out with a treadmill exercise test to see their heart rate response and blood pressure response. This should be done with an echo to determine whether they have dynamic obstruction. This information will help you guide patients on the intensity of the exercise. Start out with a low intensity and build endurance towards a moderate-intensity exercise regimen. I think an appointment with an exercise physiologist for an exercise consultation can be really helpful. Encourage your patients to really listen to their symptoms and not push beyond what they feel comfortable with, but to actively pursue a moderateintensity exercise regimen for basic health benefits. This interview has been edited for print from a transcript. To listen to the full ACCEL interview between Peter C. Block, MD, FACC, and Sara Saberi, MD, scan the QR code.
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